Slapping a whole load of sounds on top of each other usually results in a muddy incoherent mess so what are the secrets of creating a rich, full sounding, thick mix? We'll explore a few of the tips and tricks that you can use to clean up that mix.
1) Kick Drums: choose your sounds carefully, layering several kick drums with the qualities that you like can result in a thunderous speaker flapping kick, so flick through you sample collection and choose some favourites. Load them up into your sampler of choice - NI Battery is especially good for this since it gives you easy access to individual controls for each drum hit.
Now comes the fun part: try tuning each kick separately as well as filtering (high pass filters work great for cutting unwanted low frequencies from kicks) and balancing the volumes of each. You may want to shorten some of the samples down so you only get the portion of the sound that you like too. Compression with a high attack and fast release may also help to give your layered kick extra 'smack'. Layering a closed high-hat on top may also help you get some serious impact here. Once you've achieved the sound your after it makes sense to re-sample (render, bounce or what ever your DAW software calls it) your kick layers down to a single drum hit so you're only dealing with one sound, then re-import them into a single sampler instrument.
2) Bass: This can be tricky, since low frequency sounds have a nasty habit of clashing creating phasing effects, while this can be pleasing in some cases many dance genres require a constant driving bass sound.
Start off with a low frequency bass that you like the sound of, something warm and fat. Then try adding a higher mid-range layer to thicken it up - you may find that they phase, to cut this out try using a high pass or low cut filter on your mid frequency sound. Try adjusting the oscillator settings of the synths your using - this may really help to gel them together. A Little detune on the mid-range stab may help too. This really is a black art and even seasoned pro's can have difficulty getting it right so experiment! You can try using multi band distortion on some of your layers, this can really add some grit so your sound if it's needed. Another trick some producers use if they make a bass sound that they like which phases is to sample it - just sample a long note of the layered sound and use it in your favourite sampler - voila!
3) Synths: First off is good sound choice, choose your lead sounds carefully, a nice rich warm starting point will really help out as with all your layers. Once you've tweaked your first sound try adding another copy of the same sound in a higher octave - this may really help to thicken your sound. To achieve a different flavour try adding a third layer with different properties to the first, say one with a rougher edge. Pro's routinely use 4 layers for my lead sounds, often in different octaves to add depth to the synth mix. Experiment with panning here too - while this is outside the scope of this tutorial it can really help separate sounds.
Next separate your lead sound from your bass - this involves a hefty low cut or high pass filter. Start to cut around 200 Hz and adjust until your bass cuts through, but your lead sound isn't too thin and weedy. Camel Phat is a great tool for this, and of course gives you many additional control over your layered lead such as distortion and a secondary filter. I'd recommend sending all your chosen lead sounds to an Aux or Bus channel and processing them together. You may find that a light dose of overdrive or even very very light bit crusher can help tighten up and bring out your sound. A limiter may also help the overall level of sound of your synth mix from spilling over.
So some final points to bare in mind:
1) Be brutal - if it doesn't work dump it - even if it took you 2 hours. Start again! Experiment!
2) Use different sound sources - try sounds and samples from different synths, every synth has its own strengths and weaknesses and combining them can make a mighty combination. For example for lead sounds the Access Virus can be warm, wide and rich, while reFX Vanguard can sound wimpy in comparison. However the Vanguard's sparkling top end can add a layer which will make your complete layered lead sound cut through your mix.
3) Try using overdrive plugins and multi-band distortion - used lightly these effects can really help shape your mix.
4) EQ - use your ears! If it sounds wrong then hit re-set on your plugin and be gentle! On lead sounds try pulling out these frequencies: 700 Hz, 1-2 kHz, 10-12 kHz, these may help to add warmth, presence and high-end sparkle respectively.